BOG. 
Mere vegetable bog possesses nearly the same 
character in all situations and under all condi- 
tions, varying only according to its age, to the 
pressure it has undergone, and to the proportions 
of the several plants of which it is composed. 
Yet the whole extent of many bogs and large por- 
tions of others contain mixtures of mineral sub- 
stances, and very considerably vary in at once 
the quantity, the quality, and the mechanical 
conditions of these substances. Springs which 
flow into a bog frequently hold some mineral sub- 
stance in solution, and deposit it, in a permanent 
and intermixed form, in the bog. Some springs, 
for example, impregnate a bog with lime, or de- 
posit in it a mixture of calcareous earth; others 
impregnate portions of a bog with sulphur, and 
occasion peat-fuel dug from them to emit a sul- 
phurous smell during combustion ; and others 
deeply impregnate parts of bogs with iron, and 
cause the ashes of their peat to have a rusty red 
colour, indicating the presence of oxide of iron. 
But by far the largest and most important kind 
of mineral admixture is that of earths, carried 
over the surface of successive strata of bogs, by 
land floods from higher adjacent grounds. When 
a large extent of comparatively high ground de- 
clines toward a flat bog, the flow of water from 
it is great and powerful, descends in floods or tor- 
rents at every heavy fall of rain, spreads along the 
border of the bog the alluvial accumulations of 
clay, sand, and gravel, with which it is laden, 
and, making gradual advances, sometimes makes 
earthy deposits athwart every portion of the 
surface. After the alluvium acquires sufficient 
thickness to consolidate the mass, the parasitic 
musci and the eriophora and cyperacea and other 
marsh plants perish ; and land herbage succeeds, 
more or less adapted to pasture, according to the 
comparative freedom of the surface from excess 
of water. Mere vegetable moss, spongy and sa- 
turated with moisture, is the most useless and im- 
practicable kind of bog; and, on the other hand, 
moss which has becomenaturally consolidated, first 
with an alluvial deposit, and next with a sward 
of land herbage, is the most valuable and the 
least refractory. It yields from its lower strata 
a solid, warm, and lasting fuel; it affords, after 
exposure for some time to the weather, a variety 
of peat-earth which makes an excellent ingredi- 
ent of compost-manure; it is easily convertible, 
athwart its surface, into valuable meadow or pas- 
ture; and it can, at no great expense, be ren- 
dered good soil for the fruitful cultivation of 
both green and cereal crops. 
The formation of some bogs upon shallow pools 
or lakes is rendered probable by the resemblance 
of their site to the lacustrine expansion of a river- 
course, and almost or altogether certain by the 
existence of beds of shells and calcareous marl at 
their bottom. The probable process of the for- 
mation is thus stated in the Report of the Ord- 
nance Survey :—“A shallow pool induced and 
favoured the vegetation of aquatic plants, which | off by slow currents, retains most of the ingredi- 
463 
gradually crept in from the borders towards the 
deeper centre. Mud accumulated round their 
root and stalks, and a spongy semi-fluid moss 
was thus formed, well-fitted for the growth of 
moss, which now, especially sphagnum, began to 
luxuriate. This, absorbing a large quantity of 
water, and continuing to shoot out new plants 
above, while the old were decaying, rotting, and 
compressing into a solid substance below, gradu- 
ally replaced the water by a mass of vegetable 
matter. In this manner, the marsh might be 
filled up, while the central or moister portion 
continuing to excite a more rapid growth of the 
moss, it would be gradually raised above the 
edges, until the whole surface had attained an 
elevation sufficient to discharge the surface- 
water by existing channels of drainage, and cal- 
culated by its slope to facilitate their passage, 
when a limit would be in some degree set to its 
farther increase.” The surface strata sometimes 
became a floating mass by the decay of the roots 
which were attached to the ground; and they, in 
a great degree, consist of long interlaced fibres, 
which the Irish separate from the rest of the 
bog, and call old wives’ tow. The decomposed 
roots and vegetable fibres constitute a paste of 
black mud, not heavy enough to sink to the bot- 
tom, and so mixed with the water below the 
floating superficial strata as to constitute what 
is termed a quaking bog. The vegetation on the 
surface of the floating strata has often the appear- 
ance of green sward; and the roots are some- 
times so strong and matted as to form an elastic 
web-work sufficient to bear the light and rapid 
tread of an expert ‘ bog-trotter.’ 
The vegetable material of bogs does not ferment 
and decay in the rapid manner of land herbage, 
but is slowly decomposed in a similar manner to 
the duramen or perfect wood of trees. The upper 
strata of every bog which has not become car- 
peted with alluvium, or otherwise deprived of its 
purely mossy character, are always in a living or 
but very slightly decayed state; and the strictly 
superficial stratum is never older than a single 
year,—the superficial stratum of any one year 
being succeeded by a new growth in the next. 
The resistance of putrefaction on the part of the 
upper strata is the main reason why they cannot, 
in their natural state, yield nourishment to land 
plants; and it is occasioned, not by any acid or 
peculiar chemical principle in tlfe strata, but by 
the special organic constitution of the moss 
plants, by their great elasticity, and by their 
acting in both their living and their half-decayed 
state, as sponges for retaining large quantities of 
water in a stagnant condition. Moss, while un- 
decayed, is specifically lighter than water ; while 
decaying, decreases in lightness and bulk; when 
fully decayed, is comparatively compact, and 
somewhat heavier than water; and when reduced 
to its final condition, is deprived of all such por- 
tions as can be dissolved in water and carried 
